Effect of inhaled nitric oxide on cerebrospinal fluid and blood nitrite concentrations in newborn lambs.

Inhaled nitric oxide (iNO) has many extrapulmonary effects. As the half-life of nitric oxide (NO) in blood is orders of magnitude less than the circulation time from lungs to the brain, the mediator of systemic effects of iNO is unknown. We hypothesized that concentrations of nitrite, a circulating byproduct of NO with demonstrated NO bioactivity, would increase in blood and cerebrospinal fluid (CSF) during iNO therapy.

A potent, non-toxic insulin-releasing peptide isolated from an extract of the skin of the Asian frog, Hylarana guntheri (Anura:Ranidae).

Peptides in extract of the skin of the Asian frog Hylarana guntheri Boulenger,1882 were purified by reversed-phase HPLC and individual components analysed for their ability to release insulin from the rat BRIN-BD11 clonal beta cell line. The most potent peptide identified in the extract belonged to the brevinin-2 family (brevinin-2GUb; GVIIDTLKGAAKTVAAELLRKAHCKLTNSC). Other peptides with weaker insulin-releasing activity belonged to the brevinin-1 (2 peptides), brevinin-2 (2 peptides) and temporin (3 peptides) families.

The use of Lee and co-workers' index to assist a risk adjusted audit of perioperative cardiac outcome.

Lee and co-workers' revised cardiac risk index was used to study the perioperative cardiac outcome of 296 patients. The index uses a history of ischaemic heart disease, congestive cardiac failure, diabetes treated with insulin, a creatinine greater than 180 micromol/l, cerebrovascular disease and high risk surgery as the risk factors involved in predicting a perioperative cardiac event. It was derived on the basis of data from patients over the age of 50 years undergoing elective, noncardiac surgery with an expected inpatient stay of two or more days.

Signal-to-noise ratio for temporal integrated drifting images: a model for perceived image sharpening.

A formulation of signal-to-noise ratio is constructed that uses temporal integrated images from image sequences. Given a blurred image that drifts horizontally at various speeds and at various linear blurs, we prove that this formulation of the signal-to-noise ratio consistently increases with an increase in speed. This increase is shown to model the trends in the human vision system by which drifting blurred images are perceived with increased sharpness.

Insulin-releasing properties of the frog skin peptide pseudin-2 and its [Lys18]-substituted analogue.

Abstract Pseudin-2 is a cationic alpha-helical peptide that was first isolated from the skin of the paradoxical frog Pseudis paradoxa on the basis of its antimicrobial activity. We have investigated the insulin-releasing properties and cytotoxicity of the peptide, together with selected analogues with increased cationicity and hydrophobicity. At concentrations in the range 10(-9)-10(-6) m, pseudin-2, and its [Lys18], [Phe8], and [d-Lys3,d-Lys10,d-Lys14] derivatives, stimulated insulin release from the BRIN-BD11 clonal beta-cell line without increasing release of lactate dehydrogenase.

Preliminary analysis of perfusionists' strategies for managing routine and failure mode scenarios in cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) is a complex task requiring high levels of practitioner expertise. Although some education standards exist, few are based on an analysis of perfusionists' problem-solving needs. This study shows the efficacy of work domain analysis (WDA) as a framework for analyzing perfusionists' conceptualization and problem-solving strategies.

Dielectric relaxation and crystallization of nanophase separated 1-propanol-isoamylbromide mixture.

The effects of liquid-liquid phase separation on molecular relaxation of an apparently homogeneous mixture of 1-propanol and isoamylbromide has been studied by dielectric spectroscopy over a broad frequency and temperature range, and its crystallization kinetics investigated in real time. The mixture shows two widely separated relaxation processes, as before, with the faster relaxation due to the orientational diffusion of isoamylbromide and the slower due to that of 1-propanol. In the mixture, the scaled contribution to permittivity from orientation polarization, Deltaepsilon, of isoamylbromide is about the same as in the pure state, but that of 1-propanol decreases by a factor of approximately 3 at 120 K.

Structure-dependent dc conductivity and relaxation time in the Debye-Stokes-Einstein equation.

The basis for a modification of the Debye-Stokes-Einstein (DSE) equation between the dc conductivity, sigma(dc), and dielectric relaxation time, tau, has been examined by using broad-band dielectric spectroscopy of LiClO4 solutions in 5-methyl-2-hexanol and 1-propanol and of pure liquids. According to the DSE equation, the log sigma(dc)-log tau plots should have a slope of -1. We find that sigma(dc) begins to depend upon the structure of an electrolytic solution when a variation of solvent's equilibrium dielectric permittivity, epsilon(s), with temperature causes the ion population to vary.

A novel method of measuring reduction of nitrite-induced methemoglobin applied to fetal and adult blood of humans and sheep.

The reaction of nitrite with deoxyhemoglobin results in the production of nitric oxide and methemoglobin, a reaction recently proposed as an important oxygen-sensitive source of vasoactive nitric oxide during hypoxic and anoxic stress, with several animal studies suggesting that nitrite may have therapeutic potential. Accumulation of toxic levels of methemoglobin is suppressed by reductase enzymes present within the erythrocyte. Using a novel method of measuring methemoglobin reductase activity in intact erythrocytes, we compared fetal and adult sheep and human blood.

Effects of subchronic treatment with the long-acting glucose-dependent insulinotropic polypeptide receptor agonist, N-AcGIP, on glucose homeostasis in streptozotocin-induced diabetes.

Objectives: N-AcGIP is a potent and dipeptidylpeptidase IV-resistant analogue of glucose-dependent insulinotropic polypeptide with significantly improved antidiabetic actions in type 2 diabetes. The present study investigated the effects of subchronic treatment with N-AcGIP on glucose homeostasis in a type 1 model, namely, streptozotocin (STZ)-induced diabetic mice.

Methods: Swiss TO mice given a single intraperitoneal injection of STZ (150 mg/kg body weight) received once-daily injection of N-AcGIP (25 nmol/kg body weight) or saline for 20 days and effects on metabolic parameters and islet architecture assessed.

In vitro and in vivo kinetic handling of nitrite in blood: effects of varying hemoglobin oxygen saturation.

Growing evidence suggests that nitrite, acting via reduction to nitric oxide by deoxyhemoglobin, may play an important role in local control of blood flow during hypoxia. To investigate the effect of hypoxia (65 Torr arterial Po(2)) on the kinetic properties of nitrite, a bolus injection of sodium nitrite (10 mg/kg iv) was given to normoxic or hypoxic newborn lambs, and the time course of plasma nitrite and methemoglobin (MetHb) concentrations was measured. The in vivo kinetics of nitrite disappearance from plasma were biphasic and were not affected by hypoxia.

Relaxations and nano-phase-separation in ultraviscous heptanol-alkyl halide mixture.

To gain insight into the effects of liquid-liquid phase separation on molecular relaxation behavior we have studied an apparently homogeneous mixture of 5-methyl-2-hexanol and isoamylbromide by dielectric spectroscopy over a broad temperature range. It shows two relaxation regions, widely separated in frequency and temperature, with the low-frequency relaxation due to the alcohol and the high-frequency relaxation due to the halide. In the mixture, the equilibrium dielectric permittivity epsilon(s) of the alcohol is 41% of the pure state at 155.

Regulation of cytochrome oxidase redox state during umbilical cord occlusion in preterm fetal sheep.

The preterm fetus is capable of surviving prolonged periods of severe hypoxia without neural injury for much longer than at term. To evaluate the hypothesis that regulated suppression of brain metabolism contributes to this remarkable tolerance, we assessed changes in the redox state of cytochrome oxidase (CytOx) relative to cerebral heat production, and cytotoxic edema measured using cerebral impedance, during 25 min of complete umbilical cord occlusion or sham occlusion in fetal sheep at 0.7 gestation.

Role of prostanoids in the regulation of cerebral blood flow during normoxia and hypoxia in the fetal sheep.

The fetal cardiovascular responses to hypoxia include decreased peripheral blood flow and increased cerebral, cardiac, and adrenal blood flow. Prostanoids, metabolites of cyclooxygenase enzyme activity, have potent effects on vascular tone in both the adult and the fetus. To examine the role of prostanoids in the regulation of fetal cerebral blood flow (CBF) during acute hypoxic stress, eight near term fetal sheep were studied after infusing vehicle or diclofenac, a cyclooxygenase inhibitor, followed by a 30-min period of hypoxia (arterial Po(2) 12 Torr).

Protein contamination of the Laryngeal Mask Airway and its relationship to re-use.

The Laryngeal Mask Airway is a reusable device for maintaining the patency of a patient's airway during general anaesthesia. The device can be reused after it has been cleaned and sterilized. Protein contamination of medical instruments is a concern and has been found to occur despite standard sterilization techniques.

Kinetics of spontaneous change in the localized motions of D-sorbitol glass.

The dielectric relaxation spectra of D-sorbitol glass have been studied in real time during annealing at 221.1 K, which is 47 K below its T(g) of 268 K. As the glass structurally relaxes during annealing, features of the Johari-Goldstein (JG) relaxation change with time: (i) the relaxation strength decreases, (ii) the relaxation peak at 48 Hz shifts to a higher frequency, and (iii) the relaxation spectra become narrower.

Post-hypoxic hypoperfusion is associated with suppression of cerebral metabolism and increased tissue oxygenation in near-term fetal sheep.

Secondary cerebral hypoperfusion is common following perinatal hypoxia-ischaemia. However, it remains unclear whether this represents a true failure to provide sufficient oxygen and nutrients to tissues, or whether it is simply a consequence of reduced cerebral metabolic demand. We therefore examined the hypothesis that cerebral oxygenation would be reduced during hypoperfusion after severe asphyxia, and further, that the greater neural injury associated with blockade of the adenosine A(1) receptor during the insult would be associated with greater hypoperfusion and deoxygenation.

Orientation polarization from faster motions in the ultraviscous and glassy diethyl phthalate and its entropy.

Dielectric spectra of the beta relaxation in glassy and ultraviscous liquid diethyl phthalate show that its relaxation strength Delta epsilon(beta), the distribution of times, and the relaxation rate are more sensitive to temperature T in the ultraviscous liquid than in the glassy state. The Delta epsilon(beta) against temperature plot has an elbow-shaped break near T(g) of approximately 181 K, which is remarkably similar to that observed in the entropy, enthalpy, and volume against temperature plots, and in the plot of Delta epsilon(beta) against the liquid's entropy minus its 0 K value. The ratio of Delta epsilon(beta) to diethyl phthalate's entropy, after subtracting the 0 K value, is 1.

Changing patterns in the acute pain service: epidural versus patient-controlled analgesia.

This study involved an audit and a survey of the Acute Pain Service at Princess Alexandra Hospital. It was found in the audit that the relative choice of epidural analgesia had declined by 50% over the five-year time period of 1998-2003. The survey of consultants showed that 82% of them had changed their practice and that they were performing fewer epidural anaesthetics.

Parathyroid hormone-related protein production in the lamprey Geotria australis: developmental and evolutionary perspectives.

This study explored the distribution of parathyroid hormone-related protein (PTHrP) and its mRNA in tissues of the lamprey Geotria australis, a representative of one of the two surviving groups of an early and jawless stage in vertebrate evolution. For this purpose, antibodies to N-terminal and mid-molecule human PTHrP were used to determine the locations of the antigen. Sites of mRNA production were demonstrated by in situ hybridisation with a digoxigenin-labelled riboprobe to exon VI of the human PTHrP gene.

Emergency anaesthesia in a patient with Gordon's syndrome.

Gordon's syndrome is a rare condition characterized by hypertension and hyperkalemia despite normal renal glomerular function. We report the administration of an anaesthetic to one such patient for an urgent surgical procedure. The patient's serum potassium was only marginally raised at the outset of the procedure.

Dolphin Imaging Software: an analysis of the accuracy of cephalometric digitization and orthognathic prediction.

The purpose of this study was to examine and compare the reproducibility and reliability of digitization using Dolphin Imaging Software (Version 8.0) with traditional manual techniques. In addition, orthognathic prediction was compared with actual outcomes.

Protein interactions with model chromatographic stationary phases constructed using self-assembled monolayers.

Model surfaces representative of chromatographic stationary phases were developed by immobilising an homologous series (C2-C18) of n-alkylthiols, mixed monolayers of C4/C18 and thioalkanes with alcohol, carboxylic acid, amino and sulphonic acid terminal groups onto a flat, silver-coated glass surface using self-assembled monolayer (SAM) chemistry. The processes of adsorption and desorption of serum albumins onto the monolayer surfaces was monitored in real-time using surface plasmon resonance (SPR). Alkyl-terminated SAMs all showed a strong adsorption of bovine serum albumin which was largely independent of alkyl chain length, the ratio of mixed C4/C18 SAMs or the solution pH/ionic strength.

Erythrocytes are the major intravascular storage sites of nitrite in human blood.

Plasma levels of nitrite ions have been used as an index of nitric oxide synthase (NOS) activity in vivo. Recent data suggest that nitrite is a potential intravascular repository for nitric oxide (NO), bioactivated by a nitrite reductase activity of deoxyhemoglobin. The precise levels and compartmentalization of nitrite within blood and erythrocytes have not been determined.